Targeting Virulence Genes Expression in Vibrio vulnificus by Alternative Carbon Sources

Vibrio vulnificus is an opportunistic human pathogen causing self-limiting gastroenteritis, life-threatening necrotizing soft tissue infection, and fulminating septicaemia. An increasing rate of infections has been reported worldwide, characterized by sudden onset of sepsis and/or rapid progression to irreversible tissue damage or death. Timely intervention is essential to control the infection, and it is based on antibiotic therapy, which does not always result in the effective and rapid blocking of virulence. Inhibitors of essential virulence regulators have been reported in the last years, but none of them has been further developed, so far. We aimed to investigate whether exposure to some carbon compounds, mostly easily metabolizable, could result in transcriptional down-regulation of virulence genes. We screened various carbon sources already available for human use (thus potentially easy to be repurposed), finding some of them (including mannitol and glycerol) highly effective in down-regulating, in vitro and ex-vivo, the mRNA levels of several relevant -even essential- virulence factors (hlyU, lrp, rtxA, vvpE, vvhA, plpA, among others). This paves the way for further investigations aiming at their development as virulence inhibitors and to unveil mechanisms explaining such observed effects. Moreover, data suggesting the existence of additional regulatory networks of some virulence genes are reported.